[{"_id":"1","files":[{"name":"tutorial01","savedId":"id1"},{"name":"tutorial02","savedId":"id2"}]},{"_id":"2","files":[{"name":"tutorial01","savedId":"id3"},{"name":"tutorial04","savedId":"id4"}]}]

db.collection.update({"_id":"1","files.name":"tutorial01"},{"$set":{"files.$.savedId":"newId"}})